dd(1)'ing raw disk devices

[Jeffery Bacon]

I tried this on comp.unix.questions, but got a big zero, so I'll try it
here instead.

Let's suppose I do the following: (In the hypothetical realm for now:)

ctsee8(4)# /bin/dd if=/dev/rsd0c | rsh ctsee5 /bin/dd of=/dev/rsd0c

(ctsee8 is a Sun 3/60 running SunOS 4.0.3 with a 327MB scsi; ctsee5 is
a diskless 3/50 client of ctsee8, with a formatted 327MB scsi disk
attached and configured, but not being used by the machine.)

What I hope to end up with here is an exact copy of the first disk on
the second. Sure, we could partition it ourselves and use dump/restore
to do it all, but this seems quick, cheap, and just as effective.

Question is, am I doing any harm to the disk in any fashion by doing this?
I know I am copying over the partition table; I can handle that. But what
about the defect list? And mapped bad sectors? Or anything else important?
I will admit that my knowledge of disks and disk-type stuff is pretty small
(being drawn from vague Sun manuals that seem not to have been out to
teach disk stuff in the first place), so maybe the obvious won't be
too terribly obvious to me.

(btw, how can I remedy my lack of knowledge about disks in general?
Pointers to books on disks and disk-related stuff would be greatly
appreciated.)

Thanks one and all.
-------
Jeffery Bacon
Computing Technology Svcs., Michigan Technological University
bitnet: bacon at mtus5  uucp (alternate): <world>!itivax!anet!bacos